字符串拼接 拆分 NameValueCollection qscoll = HttpUtility.ParseQueryString(result)

 string result = "sms&stat=100&message=发送成功";
        string d = HttpUtility.ParseQueryString(result).Get("stat");
        string dd = HttpUtility.ParseQueryString(result).Get("message");
        string ddd = HttpUtility.ParseQueryString(result).Get("sms");
        NameValueCollection qscoll = HttpUtility.ParseQueryString(result);
        qscoll.Add("a", "nihao");
        string ss = qscoll.Get("a");
        string aaa = qscoll.ToString();

//aaa的结果sms&stat=100&message=%u53d1%u9001%u6210%u529f&a=nihao